ABSTRACTEpidemiological, clinical, and mycological studies based on a total of fifty‐eight cases of human ringworm caused byTrichophyton verrucosumwere made. They consisted of thirty‐nine epidemically occurring cases in the Tono area of Iwate prefecture in 1962 and nineteen cases occurring sporadically in Miyagi and Yamagata prefectures from 1970 through 1973. The results are summarized as follows: 1) The majority of the patients were farm workers or their family members, who had opportunity for direct contact with infected cattle. 2) The infection was most frequent during the winter months. 3) Familial occurrence was noted in twenty‐six members of eleven families. 4) The most commonly affected sites were the exposed areas of the body, particularly the forearm of an adult and the face of a child. 5) The clinical features of the lesions were classified into the following six types: agminate folliculitis, tinea circinata, kerion celsi, sycosis trichophytica, granuloma trichophyticum Majocchi, and a hyperkeratotic form of tinea manum which may be previously unreported. 6) In general, lesions showed a marked inflammation with intense erythema, edema, and pustule formation, and without central clearing. 7) The causative organism easily invades the hair follicle, so that a deep‐seated lesion may not be uncommon. 8) On comparative studies, the brain heart infusion agar (Difco) containing dextrose, peptone, thiamine HCl and antibiotics was found to be adequate for the isolation and the identification ofTrichophyton verrucosum. 9) The fungus grew more easily at 37 °C than at room temperature (25 °C), and growth was inhibited by the addition of actidione. 10) The lesions of the agminate folliculitis type and of the hairy parts should be treated orally with griseofulvin because of a possible aggravation due to topical medication.Outside of the Tohoku district of Japan a total of thirty‐eight cases have been observed in Hokkaido from 1967 to 1972 and four cases were seen in southwestern Japan in two r